#include<bits/stdc++.h>
#define exp 1e-8
using namespace std;
typedef long long ll;
const int N = 50;
ll n;
double l, r;
double a[N];
double g(double x) {
    double ret = 0;
    for(ll i = n; i >= 0; i--)
        ret = ret + pow(x, i) * a[i];
    return ret;
}
int main() {
    cin >> n >> l >> r;
    for(ll i = n; i >= 0; i--)
        cin >> a[i];
    double f, s, t;
    while(fabs(l - r) > exp) {
        s = (l + r) / 2.0;
        f = (l + s) / 2.0;
        t = (s + r) / 2.0;
        // printf("%.7lf %.7lf %.7lf\n", g(f), g(s), g(t));
        if(g(f) < g(s) && g(s) < g(t)) l = s;
        else if(g(f) > g(s) && g(s) > g(t)) r = s;
        else l = f, r = t;
    }
    printf("%.7lf\n", l);
    return 0;
}